diff --git a/CHANGELOG.md b/CHANGELOG.md
index f071043..e5f49b9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@ Latest
 ------
 
 ### Changes
+* [#65](https://github.com/cleverage/cache-process-bundle/issues/65) Configuring a key under `clever_age_cache_process` is deprecated: the bundle has no configuration and the keys were ignored without notice (new internal `Configuration`, empty; notice when the container is compiled). They will be rejected in 3.0. Require `symfony/deprecation-contracts`, used directly. Update documentation, add tests.
 * [#63](https://github.com/cleverage/cache-process-bundle/issues/63) The bundle throws exceptions implementing `ProcessExceptionInterface` of the process bundle instead of raw SPL exceptions (as [cleverage/process-bundle#317](https://github.com/cleverage/process-bundle/issues/317)): new `Exception\UnexpectedValueException`, extending the SPL exceptions thrown before (same messages, the existing `catch` keep working). `MissingAdapterException` implements `ProcessExceptionInterface`. Add tests.
 * [#61](https://github.com/cleverage/cache-process-bundle/issues/61) Composer: require PHP `^8.2` instead of `>=8.2` (PHP 9 is no longer accepted before being tested), remove the authorization of the `symfony/flex` plugin, which is not required (the CI installs it globally), as [cleverage/process-bundle#319](https://github.com/cleverage/process-bundle/issues/319).
 * [#56](https://github.com/cleverage/cache-process-bundle/issues/56) Define the public API (Symfony BC promise, as [cleverage/process-bundle#279](https://github.com/cleverage/process-bundle/issues/279)): `GetTask`, `SetTask`, `AdapterRegistry` and `CleverAgeCacheProcessBundle` are marked `@final since 2.3`, they will be `final` in 3.0: extending them triggers a deprecation with the Symfony `DebugClassLoader`. `AbstractCacheTask`, `Adapter` (extended by the applications) and `MissingAdapterException` stay open. `CleverAgeCacheProcessExtension` and `RegisterAdaptersPass` are marked `@internal`.
diff --git a/composer.json b/composer.json
index 6e39177..880e816 100644
--- a/composer.json
+++ b/composer.json
@@ -37,6 +37,7 @@
         "symfony/cache": "^6.4 || ^7.4 || ^8",
         "symfony/config": "^6.4 || ^7.4 || ^8",
         "symfony/dependency-injection": "^6.4 || ^7.4 || ^8",
+        "symfony/deprecation-contracts": "^2.5 || ^3",
         "symfony/http-kernel": "^6.4 || ^7.4 || ^8",
         "symfony/options-resolver": "^6.4 || ^7.4 || ^8",
         "symfony/polyfill-php83": "^1.33",
diff --git a/docs/index.md b/docs/index.md
index 44d378e..78a7846 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -47,6 +47,8 @@ services:
             - { name: cleverage.cache.adapter, code: app }
 ```
 
+No option can be configured under `clever_age_cache_process`: a key there is ignored. Configuring one is deprecated since 2.3 (an `E_USER_DEPRECATED` error is triggered when the container is compiled), the keys will be rejected in 3.0.
+
 ## Custom cache tasks
 
 `CleverAge\CacheProcessBundle\Task\AbstractCacheTask` can be extended to implement other cache operations. It extends
diff --git a/src/DependencyInjection/CleverAgeCacheProcessExtension.php b/src/DependencyInjection/CleverAgeCacheProcessExtension.php
index bb9b109..e8f48ab 100644
--- a/src/DependencyInjection/CleverAgeCacheProcessExtension.php
+++ b/src/DependencyInjection/CleverAgeCacheProcessExtension.php
@@ -31,6 +31,18 @@ class CleverAgeCacheProcessExtension extends Extension
 {
     public function load(array $configs, ContainerBuilder $container): void
     {
+        $keys = array_keys(array_merge(...$configs));
+        if ([] !== $keys) {
+            trigger_deprecation(
+                'cleverage/cache-process-bundle',
+                '2.3',
+                'Configuring "%s" is deprecated, the bundle has no configuration: the keys "%s" are ignored. They will be rejected in 3.0.',
+                $this->getAlias(),
+                implode('", "', $keys),
+            );
+        }
+        $this->processConfiguration(new Configuration(), $configs);
+
         $this->findServices($container, __DIR__.'/../../config/services');
 
         $container->registerAttributeForAutoconfiguration(
diff --git a/src/DependencyInjection/Configuration.php b/src/DependencyInjection/Configuration.php
new file mode 100644
index 0000000..16bf225
--- /dev/null
+++ b/src/DependencyInjection/Configuration.php
@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the CleverAge/CacheProcessBundle package.
+ *
+ * Copyright (c) Clever-Age
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CleverAge\CacheProcessBundle\DependencyInjection;
+
+use Symfony\Component\Config\Definition\Builder\ArrayNodeDefinition;
+use Symfony\Component\Config\Definition\Builder\TreeBuilder;
+use Symfony\Component\Config\Definition\ConfigurationInterface;
+
+/**
+ * The bundle has no option: the configured keys are ignored with a deprecation (see CleverAgeCacheProcessExtension::load()), they will be
+ * rejected in 3.0.
+ *
+ * @internal
+ */
+final class Configuration implements ConfigurationInterface
+{
+    public function getConfigTreeBuilder(): TreeBuilder
+    {
+        $treeBuilder = new TreeBuilder('clever_age_cache_process');
+        /** @var ArrayNodeDefinition $rootNode */
+        $rootNode = $treeBuilder->getRootNode();
+        $rootNode->ignoreExtraKeys();
+
+        return $treeBuilder;
+    }
+}
diff --git a/tests/DependencyInjection/CleverAgeCacheProcessExtensionTest.php b/tests/DependencyInjection/CleverAgeCacheProcessExtensionTest.php
index 27c4678..db2ece2 100644
--- a/tests/DependencyInjection/CleverAgeCacheProcessExtensionTest.php
+++ b/tests/DependencyInjection/CleverAgeCacheProcessExtensionTest.php
@@ -15,6 +15,7 @@
 
 use CleverAge\CacheProcessBundle\Attribute\AsCacheAdapter;
 use CleverAge\CacheProcessBundle\DependencyInjection\CleverAgeCacheProcessExtension;
+use CleverAge\CacheProcessBundle\DependencyInjection\Configuration;
 use CleverAge\CacheProcessBundle\Registry\AdapterRegistry;
 use CleverAge\CacheProcessBundle\Task\GetTask;
 use CleverAge\CacheProcessBundle\Task\SetTask;
@@ -32,6 +33,7 @@
 use Symfony\Component\Yaml\Yaml;
 
 #[CoversClass(CleverAgeCacheProcessExtension::class)]
+#[CoversClass(Configuration::class)]
 #[UsesClass(AdapterRegistry::class)]
 #[CoversClass(AsCacheAdapter::class)]
 class CleverAgeCacheProcessExtensionTest extends TestCase
@@ -149,6 +151,54 @@ public function testTaskIsRegistered(string $class, string $code, string $deprec
             $alias->getDeprecation($deprecatedId)
         );
     }
+
+    public function testConfigurationKeysAreDeprecated(): void
+    {
+        $deprecations = $this->collectDeprecations(static function (): void {
+            (new CleverAgeCacheProcessExtension())->load([[], ['foo' => true], ['bar' => 1, 'foo' => false]], new ContainerBuilder());
+        });
+
+        self::assertSame(['Since cleverage/cache-process-bundle 2.3: Configuring "clever_age_cache_process" is deprecated, the bundle has no configuration: the keys "foo", "bar" are ignored. They will be rejected in 3.0.'], $deprecations);
+    }
+
+    public function testNoDeprecationWithoutConfigurationKey(): void
+    {
+        $deprecations = $this->collectDeprecations(static function (): void {
+            (new CleverAgeCacheProcessExtension())->load([[], []], new ContainerBuilder());
+        });
+
+        self::assertSame([], $deprecations);
+    }
+
+    public function testConfigurationHasNoOption(): void
+    {
+        $configuration = (new CleverAgeCacheProcessExtension())->getConfiguration([], new ContainerBuilder());
+
+        self::assertInstanceOf(Configuration::class, $configuration);
+        self::assertSame('clever_age_cache_process', $configuration->getConfigTreeBuilder()->buildTree()->getName());
+    }
+
+    /**
+     * @param callable(): void $callback
+     *
+     * @return list<string>
+     */
+    private function collectDeprecations(callable $callback): array
+    {
+        $deprecations = [];
+        set_error_handler(static function (int $errno, string $errstr) use (&$deprecations): bool {
+            $deprecations[] = $errstr;
+
+            return true;
+        }, \E_USER_DEPRECATED);
+        try {
+            $callback();
+        } finally {
+            restore_error_handler();
+        }
+
+        return $deprecations;
+    }
 }
 
 final readonly class AutowiredRegistryConsumer